Crystal growth, structure and magnetic frustration in rare earth pyrochlore oxides

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• Monica Ciomaga Hatnean, University of Warwick
• Wednesday 21 February 2018, 11:15-12:30
• Mott Seminar Room (531), Cavendish Laboratory, Department of Physics.

If you have a question about this talk, please contact Romy Hall.

Pyrochlore oxides, A2B2O7 (where A = Rare Earth, B = Transition Metal) are one of the most studied and puzzling classes of materials, due to their characteristic crystallographic structure (both A and B sites form a 3D network or corner-sharing tetrahedra) and exotic magnetic properties, such as spin ice, spin glass, spin liquid behaviour or long-range magnetic ordered states [1,2]. Significant progress has been made in the two past decades in the study of pyrochlore frustrated magnets due to the availability of large, high quality single crystals of rare earth titanium and molybdenum oxides [3]. One of the most exciting avenues of future research is into systems which exhibit novel magnetic ground states, such as quantum spin liquid and quantum spin ice. As the search for frustrated magnets that display quantum effects widens, the research community has turned its attention to less studied pyrochlore systems, such as rare earth zirconates and hafnates R2M2O7 (R = Rare Earth, M= Zr or Hf). Recent advances in the crystal growth by the floating zone method of pyrochlore oxides with high melting temperatures has opened a route to further investigations of the zirconate and hafnate families of frustrated magnets [4,5]. I will cover the recent developments in the synthesis of large high-quality crystals of these novel classes of pyrochlore oxides and discuss briefly the challenges associated with their growth, such as evaporation, mixed valence states, structural phase transitions [6-8]. I will present a detailed structural and magnetic study of members of the zirconate and hafnate series of pyrochlore oxides, and I will show how structural defects affect the fascinating magnetic behaviours of these materials [8-10].

[1] M. A. Subramanian, Progress in Solid State Chemistry 15, 55 (1983). [2] J. S. Gardner, Reviews of Modern Physics 82, 53 (2010). [3] G. Balakrishnan, Journal of Physics: Condensed Matter 10, L723 (1998). [4] K. Matsuhira, Journal of Physics: Conference Series 145, 012031 (2009). [5] J. Chun, Journal of Materials Chemistry C 3 , 491 (2015). [6] M. Ciomaga Hatnean, Journal of Crystal Growth 418, 1 (2015). [7] M. Ciomaga Hatnean, Journal of Physics: Condensed Matter 29, 075902 (2017). [8] R. Sibille, Nature Communications 8, 892 (2017). [9] S. Petit, Nature Physics, 12, 746 (2016). [10] N. Martin, Physical Review X 7 , 041028 (2017).

This talk is part of the Quantum Matter Seminar series.

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